update template code

mmp/a3/annotation.py

@@ -0,0 +1,27 @@
+from typing import List
+import numpy as np
+
+
+class AnnotationRect:
+    """Exercise 3.1"""
+
+    def __init__(self, x1, y1, x2, y2):
+        raise NotImplementedError()
+
+    def area(self):
+        raise NotImplementedError()
+
+    def __array__(self) -> np.ndarray:
+        raise NotImplementedError()
+
+    @staticmethod
+    def fromarray(arr: np.ndarray):
+        raise NotImplementedError()
+
+
+def read_groundtruth_file(path: str) -> List[AnnotationRect]:
+    """Exercise 3.1b"""
+    raise NotImplementedError()
+
+
+# put your solution for exercise 3.1c wherever you deem it right